<html>
 <head>
  <title>标题</title>
  <style type="text/css">
     div {
          width:100px;
          height:100px;
          margin:20px;
          background:pink;
}
  #sss {background:blue;}
  .zzz {background:pink;}
   </style>
</head>
<body>
  <div class="zzz"></div>
  <div id="sss"></div>
  <div class="zzz"></div>
</body>
</html>
